Filament shield



Feb. 6, 1962 H. c. MEAD 3,020,435

FILAMENT SHIELD Filed June 29, 1960 IN VEN TOR.

[A TTOPNEY Unite rates The present invention relates to vehicle headlamps having two filaments which are adapted to selectively produce either a high or road beam or a low or depressed passing beam and, in particular, to a shield for intercepting certain glare-producing light rays directed forwardly from the lower beam filament both above and below a horizontal plane approximately through the filament.

Conventional automobile headlamps currently in use today typically comprise an all-glass concave or generally paraboloidal reflector and dished cover glass or lens having their mating peripheries fused together to form a sealed envelope enclosing two filaments adapted to be selectively energized to provide a high or low beam. Each of the filaments is axially coiled and fixedly mounted within the lamp envelope with its major axis generally I horizontal and parallel to the axis of the other filament. Moreover, these filaments are positioned in a predetermined position with respect to each other and the focus of the reflector depending upon the particular type of lamp in question. a

For example, in one type of automobile headlamp presently in use, the upper beam filament is disposed horizontally within the reflector and is located approximately at the focus of the reflectoigwhile the lower beam filament is located slightly above and to one side of the upper beam filament. In another type of headlamp, commonly referred to as a Type II lamp, the horizontally disposed lower beam filament is located approximately at the focus of the reflector, while the upper beam filament is located slightly below and to one side of the lower beam filament. In passing, it might be noted that one variety of such a Type II lamp is known as a seveninch lamp because of its diameter, and is employed in a single lamp installation on each side of the front of the vehicle. Another variety of such a Type II lamp is known as a five and three-quarter inch lamp, and is utilized in dual lamp installations on each side of the front fender of the vehicle.

Irrespective of the particular type of headlamp involved, the dual filaments of any given lamp are adapted to be selectively energized to provide either a high symmetrical road beam suitable for country driving purposes, or a lower or depressed asymmetric beam suitable for use when passing other vehicles. To this end, the lamp lens is provided with suitable light-distributing media such as light-spreading flutes and vertically up-bending and down-bending prisms to provide the aforementioned road and passing beams meeting specifications as set therefor by the motor vehicle industry. However, because of the particular character of such light-distributing media, and particularly the vertically up-bending and down-bending prisms, a problem is presented with respect to an appreciable amount of upward and downward spill light which is unavoidably produced from the lower beam filament of the headlamp. Such spill light becomes an annoying and sometimes blinding glare when reflected into the eyes of the vehicle operator by fog, snow, rain, dust and the like, or directed into the eyes of the operator of an oncoming vehicle.

At this juncture, it should be noted that such spill or glare light is occasioned not only by light rays directed upwardly from the filament, but also from direct light rays which pass forwardly and downwardly through the lens and are refracted downwardly further by the lightdistributing media on the lens so as to stlike highly polished surfaces protruding forwardly from the plane of the headlamps, such as chrome-coated bumpers and trim. As a consequence, such direct downward filament light is redirected upwardly by such highly polished surfaces.

Thus, in certain vehicle installations, the problem of up,- ward spill or glare light may be occasioned by light rays provide a filament shield of the type aforementionedwhich, while intercepting direct light rays projected forwardly from a filament both above and below a horizontal plane through the filament, still permits passage of certain unobjectionable light rays which are then available for side-lighting or lighting areas generally to either side of the path of the vehicle.

In general, these and other objects and features of this invention are attained in a headlamp construction of the type comprising two vertically spaced laterally offset generally horizontal axially coiled filaments adapted to be selectively energized to produce either a high or low beam of the required characteristics, and a light-intercepting shield disposed immediately in front of the filaments and having spaced upper and lower portions in predetermined positions with respect to the lower beam filament so as to intercept a substantial portion, but not all, of the light rays directed forwardly from the lower beam filament both above and below a horizontal plane approximately, through the filament, while permitting passage throughthe shield of certain remaining and selected light rays which are available for lighting the side of the roadway, street signs and the like, while not resulting in any objectionable glare.

The manner in which the foregoing objects are attained will become more apparent hereinafter as the description of the invention proceeds, and in which reference is made to the following drawings in which:

FIGURE 1 is a vertical section through a modern vehicle headlamp equipped with the invention, and is taken.

on line 11 of FIGURE 2;

FIGURE 2 is a fragmentary front elevation of a modern day automobile headlamp equipped with the present invention, with certain parts broken away to illustrate certain details of the invention; t

FIGURE 3 is an enlarged section taken on line 33 of FIGURE 2; and

FIGURE 4 is an enlarged plan view of the filament shield of FIGURE 2.

Referring now to the drawings, the numeral 2 indicates an all-glass sealed beam lamp comprising a concave or generally paraboloidal reflector 4 having a suitable reflective coating on its inner surface 6, and a dish shaped lens 8. The peripheral rims of the lens. and reflector are fused together as indicated at 10 to form a sealed envelope for the dual sources of concentrated light in the form of an axially coiled generally horizontally disposed lower beam filament 12 and a similarly formed and disposed upper beam filament 14. As is the usual practice, the two coiled filaments are suspended within the lamp envelope on the inner ends of a suitable number of lead wires, indicated generally at 16, which extend through the base of the reflector 4 and are electrically and mechanically connected to the thimble-like contact; structures 18 accessible from the exterior of the reflector. Inasmuch as the lamp illustrated is of the Type II variety, the lower beam filament 12 is located approximately at the focus of the reflector, although not necessarily exactly centered laterally thereon. The upper beam filament 14 is located slightly beiow and offset to the left from the lower beam filament 12 as viewed in FIGURES 2 and 4.

The light-distributing lens 8 of the headlamp is provided in the usual manner with suitable light-distributing media, preferably on the inner surface of the lens, for distributing the rays of light projected from the reflecting surface 6 so as to produce, upon selective energization of the filaments 12 and 14, a lower passing beam and an upper driving beam conforming to the specifications set therefor by the motor vehicle industry. For this purpose, and according to conventional practice, the lens 8 is divided into a series of sections or patches which are provided as required with a plurality of small lightspreading flutes for horizontally spreading the light passing through the lens. As is well known in the art, certain of such flutes in diiferent portions of the lens provide different degrees of spread in order to impart the required horizontal spread to the beams projected by the lamp. Furthermore, certain of the sections or patches of the lens are provided with vertically tip-bending and down-bending prisms indicated at 2% in FIGURE 1 so as to refract the light rays passing therethrough to provide the required vertical distribution of the light in the beams projected by the lamp.

In the manufacture of lenses provided with such prisms 20 for bending light rays vertically, the ends or extremities of the prisms must be provided with a slight amount of draft in order to permit separation of the lens from the pressing plunger of the molding apparatus. As is well known in the art, the bases of such prisms have rounded corners which constitute, in conjunction with the base surface itself, small secondary lenses which direct the rays of light striking it in a direction opposite to that of the rays refracted by the prism itself. These corners of the aforementioned down-bending prisms, as well as the flat base surfaces thereof, direct the rays of light striking them upward from the headlamp. Consequently, these corners and base surfaces of the down-bending prisms constitute sources of light in. the lens itself which create a considerable amount of upward spill and glare light which, when added to the upward direct light from the lower beam filament 12, creates an upwardly directed curtain of spill and glare light from the headlamp which may become blinding when reflected back into the eyes of the driver by fog, mist, rain, snow, dust and the like, as well as into the eyes of a driver of an oncoming vehicle. In similar fashion, such corners and flat base surfaces of the upbcnding prisms constitute secondary sources of light in the lens itself which create a considerable amount of downward spill light which is reflected from highly refiective portions of the vehicle protruding in front of the headlamps, such as the front bumper, and is directed upwardly to provide an additonal source of glare light.

In order to reduce, although not eliminate, this problem of glare at least with respect to light from the lower beam filament directed forwardly therefrom and above a horizontal plane, it is common practice in some lamps to tilt the axis of reflecting surface 6 downwardly at a slight angle from the horizontal plane, and also to the right a few degrees when viewed from behind the reflector. Such an expedient aids in properly directing the lower beam projected from the filament 12 down and to the right when viewed from the vehicle operators compartment, although the light-distributing media aforedescribed is still required for complete distribution of the desired lower beam as well as the upper beam. However, by so tilting the reflector axis relative to the horizontal, and as is well known in the art, the glare effect from direct upward spill light from the lower beam filament is to some extent minimized, although far from eliminated.

Having described a conventional and well known lamp construction and the glare problem introduced thereby, reference will now be made to the filament shield 22 which not only substantially eliminates the problem of glare from direct upward spill light from the filament 12, but also the similar problem occasioned by downward spill light which is susceptible to refraction by the draft corners and bases of the vertically up-bending prisms so as to be directed toward and rte-reflected upwardly from highly polished surfaces on the vehicle protruding forwardly from the lamp.

Referring particularly to FIGURE 4, the filament shield 22 may be seen to have a generally bow-tie in that it comprises vertically spaced upper and lower shield sec tions 24- and 26, respectively, joined by a relatively nar' row and integral centrally located bridge or neck portion 28. More specifically, the upper shield section 24 is in the form of a truncated 160 sector of a circle, with the truncated edge thereof joined or formed integral with the upper portion of the bridge or neck 28 as indicated in dotted lines at 30. In similar fashion, the lower shield section 26 is in the form of a truncated sector of the same circle from which the upper shield section is sectorized, and is formed integral with and joined to the lower portion of the bridge 28 as indicated in dotted lines at 32.

The neck 28 rigidly joins and vertically spaces the upper and lower shield portions from each other so as to provide notches or openings between the shield sections on each side of the neck 28. The upper shield section 24 is symmetrically disposed on either side of a vertical plane through the center C of the shield so that the radial edges 34 thereof extend upwardly at an angle of approximately 10 with the horizontal. In similar fashion, the lower shield section 26 is symmetrically disposed with respect to the aforementioned vertical plane with the radial edges 36 thereof extending downwardly at an angle of approximately 40 with the horizontal. Thus, and as will appear more fully hereinafter, the notches or openings in the shield formed by the neck 28 and the opposed radial edges 34 and 36 of the shield sections will permit direct light to pass from the lower beam filament 12 slightly above and to a greater extent below a horizontal plane through the center C of the shield. The arcuate edge portions of the upper and lower sector-shaped shield sections each include a flange 38 which is bent axially rearwardly at a right angle to the plane of the shield sections to provide additional light-intercepting surfaces, while a Y-shaped depression 40 centrally and symmetrically disposed with respect to the shield 22 provides reinforcement therefor.

From the foregoing description, it may be seen that the shield 22 may be manufactured from a circular sheet of material, such as sheet metal, by notching the circular sheet radially inwardly from opposed portions of the periphery thereof to define the upper and lower shield sections 24 and 26 and connecting bridge 28 therebetween, followed by bending of the flanges 38 axially rearwardly as aforedescribed.

A wire 42 is suitably secured as indicated at 44 to the upper shield section 24, and similarly secured to one of the lead Wires 16 so as to mount the shield immediately in front of the filaments 12 and 14. More specifically, and referring again to FIGURE 4, the shield is preferably positioned so that a vertical plane through the center C" thereof passes approximately through the mid-point of lower beam filament 12, while a horizontal plane through the center C generally contains the lower edge of the filament coil. Moreover, the axis of filament coil 12 is approximately in the horizontal plane containing the lower edge indicated at 30 of upper shield section 24. The upper beam filament 14 is correspondingly located in accordance with its displacement from the filament 12 as previously described, it being noted that this filament is less shielded.

Consequently, with the lower beam filament 12 energized, the upper shield section 24 will intercept substan tially all glare-producing light rays directed forwardly and above a horizontal plane generally through the center of the shield or the axis of the lower beam filament; that is, the upper shield section will intercept such direct light rays in the solid angle subtended by approximately 160 of the upper half of the lens 8. In similar fashion, the lower shield section 26 will intercept glare-producing light rays directed forwardly from the lower beam filament 12 below the horizontal plane aforementioned, and in the angle subtended by approximately 100 of the lower half of the lamp lens 8. On the other hand, the notches or openings formed between the opposed shield sections to either side of the neck 28 permit direct light rays from the lower beam filament 12 to pass therethrough and through the lens toward either side of the vehicle for sidelighting purposes and, while consisting substantially of light below the aforementioned horizontal plane, some light passes above said plane for illuminating signs and the like along the roadway.

From the foregoing description, it may be seen that the filament shield 22 is constructed and arranged relative to the lower beam filament 12 and the lens 8 so as to intercept glare-producing lightrays directed forwardly from the filament both above and below the horizontal to prevent corresponding critical areas of the lens from a glareproducing standpoint from receiving any such rays, while at the same time permitting unobjectionable direct light rays to pass through the openings on either side of the shield for side-lighting purposes. Viewed in another way, an area on the inner surface of the lens 8 corresponding to the configuration of the shield 22 is masked from any such objectionable direct rays from the filament 12, while two generally horizontally opposed portions on the lens are unmasked and will receive and transmit direct light rays from the lower beam filament for side-light purposes. In this regard, it will be appreciated that the portions of a lens to be masked or shielded will depend upon variables such as the tilt of the reflector, the location of the filament 12 and the particular nature and arrangement vof the lightdistributing media on the lens in accordance with the character of the projected beams desired. Thus, the angular extent of the upper and lower shield sections may be varied in accordance with such considerations.

While but one form of the invention has been shown and described, other forms will now be apparent to those skilled in the art. Therefore, the embodiment shown in the drawings is merely for illustrative purposes, and is not intended to limit the scope of the invention which is defined by the claims which follow.

I claim:

1. A vehicle headlamp comprising a substantially paraboloidal reflector, a first coiled filament disposed in a substantially horizontal plane and approximately at the focus of said reflector, a second coiled filament disposed generally parallel to and spaced a slight distance below and to one side of said first filament, a lens covering said reflector and provided with vertically up-bending and down-bending prisms for distributing light rays reflected by said reflector upon selective energization of said filaments to provide a lower beam from said first filament and an upper beam from said second filament, a filament shield comprising an upper shield section having the shape of a truncated 160 sector of a circle and being disposed substantially entirely above said horizontal plane to intercept glare-producing light rays from said first filament in the solid angle subtended by 160 of the upper half of said lens, a lower shield section having the shape of a truncated sector of said circle and being disposed substantially entirely below said horizontal plane to intercept direct glare-producing light rays from said first filament in the solid angle subtended by 100 of the lower half of said lens, and a relatively narrow centrally located bridge integral with and joining said shield sections to define openings in said shield between said shield sections on each side of said bridge to permit passage therethrough of selected direct light rays from said first filament toward the unshielded portions of said lens, a substantial portion of said second filament being located opposite one of said openings in said shield whereby a substantial portion of the light rays therefrom in excess of said selected light rays from said first filament is permitted to pass through said opening toward an unshielded portion of said lens.

2. A vehicle headlamp comprising a substantially paraboloidal reflector, a first coiled filament disposed in a substantially horizontal plane, a second coiled filament disposed generally parallel to and spaced a slight distance vertically and to one side of said first filament, one of said filaments being located approximately at the focus of said reflector, a lens covering said reflector and provided with vertically up-bending and down-bending prisms for distributing light rays reflected by said reflector upon selective energization of said filaments to provide a lower beam from said first filament and an upper beam from said second filament, a filament shield comprising an upper shield section having the shape of a truncated sector of a circle and being disposed substantially entirely above said horizontal plane to intercept glare-producing light rays from said first filament in the solid angle subtended by less than all of the upper half of said lens, a lower shield section having the shape of a truncated sector of said circle and being disposed substantially entirely below said horizontal plane to intercept direct glare-producing light rays from said first fila ment in the solid angle subtended by less than all of the lower half of said lens, and a relatively narrow centrally located bridge integral with and joining said shield sections to define openings in said shield between said shield sections on each side of said bridge to permit passage therethrough of selected direct light rays from said first filament toward the unshielded portions of said lens, a substantial portion of said second filament being located opposite one of said openings in said shield whereby a substantial portion of the light rays therefrom in eXcess of said selected light rays from said first filament is permitted to pass through said opening toward an unshielded portion of said lens.

Reynolds Apr. 23, 1935 Flaws et al Mar. 31, 1959 

